I just got an Xserve off ebay for 175$ shipped with 96gb of ddr3, 3x160gb sas drives in raid 0, and 2x750w psu. I've upgraded the processors to the max for 40$, 2x W5590's. Its hashing in high sierra using the luckyminer osx app at 1030 h/s (my 3770k @ 4.3ghz only gets 840 h/s). I know the power consumption is high but the bang for the buck is there.